The repeated presentation of an identical visual stimulus in the receptive field of a neuron may evoke different spiking patterns at each trial. Probabilistic methods are essential to understand the functional role of this variance within the neural activity. In that case, a Poisson process is the most common model of trial-to-trial variability. For a Poisson process, the variance of the spike ...

Premature beats can trigger ventricular arrhythmias in heart disease, but the mechanisms are not well defined. We studied the effect of premature beats on activation and repolarization dispersion in seven patients with cardiomyopathy (57 ± 10 yr, left ventricular ejection fraction 31 ± 7%). Activation time (AT), activation-recovery interval (ARI), and total repolarization time (TRT) were measur...

ramadan fasting is one of the most important religious duties of muslims, that its effect on the heart has not been determined yet. our objective was to evaluate the effect of ramadan fasting on ventricular repolarization as assessed by qt interval, corrected qt interval, qt dispersion or corrected qt dispersion. sixthy healthy subjects aged 20 to 35 years were dispersion included in this study...

We present the first treatment of the refraction of physical electromagnetic waves in newly developed negative index media (NIM), also known as left-handed media (LHM). The NIM dispersion relation implies that group fronts refract positively even when phase fronts refract negatively. This difference results in rapidly dispersing, very inhomogeneous waves. In fact, causality and finite signal sp...

We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess a negative shear modulus and negative mass density over a large frequency region. Such a material has the unique property that only transverse waves can propagate with a negative dispersion while longitudinal waves are forbidden. This leads to many interesting phenomena such as negative refra...

We study the strategic behavior of equity analysts whose compensation is based on relative performance of their stock recommendations. Our model predicts that riskaverse analysts issue identical recommendations to avoid falling behind their peers. Top analyst awards, on the other hand, motivate analysts to issue bold recommendations. However, when the stock return is very volatile, the herding ...

A pulsed mid-infrared pump at λ=2173 nm is used to demonstrate wideband optical parametric gain in a low-loss 2 cm long silicon photonic wire. Using dispersion engineering to obtain negative second-order (β2) and positive fourth-order (β4) dispersion, we generate broadband modulation instability and parametric fluorescence extending from 1911 nm-2486 nm. Using a cw probe signal to interrogate t...

We investigate the dispersion of the charge carrier plasmon in the three prototypical charge-density wave bearing transition-metal dichalcogenides 2H-TaSe(2), 2H-TaS(2), and 2H-NbSe(2) employing electron energy-loss spectroscopy. For all three compounds the plasmon dispersion is found to be negative for small momentum transfers. This is in contrast with the generic behavior observed in simple m...

This paper presents a modal analysis of a uniaxial grounded chiroslabguide. A dispersion model with a single resonance is used to describe the physical properties of the chiral uniaxial medium. We show that proper leaky modes can propagate regardless of the sign (positive or negative) of the medium’s parameters. Furthermore, proper leaky modes can also occur as a consequence of electromagnetic ...

Power and sample size calculation is an essential component of experimental design in biomedical research. For RNA-sequencing experiments, sample size calculations have been proposed based on mathematical models such as Poisson and negative binomial; however, RNA-seq data has exhibited variations, i.e. over-dispersion, that has caused past calculation methods to be underor over-power. Because o...